Purpose::
Primary Open Angle Glaucoma (POAG) is a major blinding diseasethat disproportionately affects individuals of West Africandescent. We have collected 25 African American and 12 Ghanaianmultiplex families suitable for genomic linkage analysis toidentify regions harboring susceptibility genes for glaucomain populations of African origin.

Methods::
The Illumina Bead Station platform (Linkage Panel IV) was usedto genotype these 37 POAG families. After excluding markersthat did not meet quality control criteria, 5067 SNPs were analyzedwith standard linkage methods. Allele frequencies were verysimilar in the African American and Ghanaian individuals, soresults from both groups were combined during analysis. Someof these families were previously found to carry sequence variantsin MYOC that do not segregate with disease status. Other familieshave been linked to the GLC1I locus on chromosome 15. Linkageanalysis was conducted both on the entire dataset, and afterremoving these subgroups.

Results::
We have detected linkage to 2q22-24 with a peak non-parametricLOD* score of 1.7, increasing to 2.3 after removing familieslinked to GLC1I or carrying MYOC variants. This suggestive linkagecorresponds to a peak previously identified by the BarbadosFamily Study Group. The peak gave a three-point lod score ofover 3.5 upon fine mapping (markers D2S117 and D2S2189).

Conclusions::
Independent replication in multiple independent datasets isextremely powerful in identifying real linkages that harborsusceptibility genes. We have identified suggestive linkagefor POAG in our African American / Ghanaian family dataset,which corresponds to that previously reported in the Barbadosfamily dataset. This replicated peak is being followed up inthe Barbados dataset, as well as the African American and Ghanaianfamilial and case/control datasets.